Quick answer
Color is decided long before the display is assembled — it comes from the semiconductor material of the die and from how that die is manufactured. Factories focus on mass-producing commonly used colors to reduce production costs. Selecting from existing LED color series helps minimize overall product cost.
Table of Contents
Choose lowest-cost colored LED for your product!
A light-emitting diode (LED) is a two-terminal semiconductor that emits light when forward current flows through the junction. A voltage above the forward voltage V_F is what allows that current to flow; the light output tracks the current, not the voltage. The emitted light color is determined by the materials and manufacturing process used, as well as other electronic characteristics. Each LED is designed to emit a specific color based on its material and manufacturing. In cases where a product requires a particular color or color change, Red, Green, and Blue (RGB) LEDs are used in combination to create the desired color using the RGB color model. Please note that this paragraph does not cover the RGB color model; instead, it focuses on choosing the most cost-effective colored LED for your product.
Why do product designers need the lowest-cost colored LED?
Theoretically, any LED color can be achieved by adjusting the materials and manufacturing process. However, producing every possible LED color would result in extremely high production costs for LED factories. To reduce costs and ensure profitability, LED factories focus on mass-producing the most commonly used colored LEDs.
You can think of an LED as a light bulb. When a light bulb is powered correctly, it emits light with a specific color and brightness that was determined during the manufacturing process. To minimize costs, factories choose a range of LEDs with the most commonly used colors and brightness levels. RGB light bulbs are used for applications requiring specific colors instead of creating a unique color for each instance. By selecting from existing LED color series for your product, you can reduce the overall cost.
How to express color in LED?
Expressing a specific color can be challenging. For example, consider the blue color shown in the picture below.
Different individuals may perceive this blue differently, such as sky blue, water blue, or even Ferrari blue. Additionally, factors like variations in monitors and printing can affect how colors appear.
To address this, some companies have developed color card systems, such as the Pantone color system, to ensure consistent color representation throughout the design process.
In the case of Light-Emitting Diodes (LEDs), we use the wavelength of emitted light to express the color. Following the visible light spectrum, we classify visible light into seven colors: red, orange, yellow, green, cyan, blue, and violet.
Most commonly used LED emitting colors for LED makers:
The most frequently used LED emitting colors are blue, amber, orange-red, red, yellow, yellow-green, and pure green. The following table shows the color names and corresponding colors.
Sometimes, the color “orange-red” may also be referred to as “red-orange.” Both expressions denote the same color, which lies between orange and red. However, it is uncommon to refer to yellow-green as green-yellow. Additionally, white is another commonly used LED emitting color. However, discussing the details of white color goes beyond the scope of this article.
If you require a color not listed in the table above, it would require a custom LED, which comes at a higher price. Therefore, it is important to choose the right color for low-budget product designs.
Wavelength range for the 7 most commonly used LED emitting colors:
Each LED display uses different LEDs, and the color name on the datasheet is only an approximate description — always specify the dominant wavelength (λD) range instead.
The OPTO PLUS emitting color code table
Why does the color decision belong at the start of a project, not the end? Because the emitting color decides three things at the same time: the unit cost, the forward voltage class of your circuit, and the brightness balance of the panel. The table below is the official color code list used in every OPTO PLUS part number, together with the chip material and the typical wavelength.
| Code | Color | Chip material | Typical wavelength (nm) |
|---|---|---|---|
| W | Super Bright White | InGaN | CIE x, y coordinates |
| B | Super Bright Blue | InGaN | 470 |
| PG | Pure Green | InGaN | 525 |
| G | Yellow Green | GaP | 570 |
| YG | Super Bright Yellow Green | AlGaInP | 570 |
| Y / LY | Yellow / Super Bright Yellow | GaAsP / AlGaInP | 590 |
| A / LA | Amber / Super Bright Amber | GaAsP / AlGaInP | 610 |
| E / LE / UE | High Efficiency Red / Super Bright Red | GaAsP / AlGaInP | 625 |
| SR | Super Red | AlGaInP | 640 |
| H | Red | GaP | 640 |
Different wavelength ranges for each LED emitting color
For every LED maker, the wavelength range for the same color may vary. For example, the amber color in OPS-S5620(1)SA and OPD-M25710(1)LA has different wavelength ranges. It is important to check the specific wavelength range when the application requires an exact colored LED.
The same color name does not mean the same wavelength
A color name is a catalog label, not a specification. The amber in OPS-S5620(1)SA and the amber in OPD-M25710(1)LA have different wavelength ranges. When your product needs color matching between different displays, or between a display and a light pipe, please specify the dominant wavelength (λD) range from the datasheet instead of the color name.
Your color choice also decides your circuit design
The common colors belong to two forward voltage classes. Red, amber, and yellow class parts operate at about 2.0–2.4 V. Blue, pure green, and white parts use InGaN chips and operate at about 2.8–3.4 V. If you change the color late in the project, the resistor values and the supply voltage budget may need to change as well. We suggest choosing the color family before the drive circuit is finalized.
Brightness at the same current is also different for each color. In one of our 12-bar displays, the typical luminous intensity is 15 mcd for red, 40 mcd for yellow, and 20 mcd for yellow green at 20 mA. A panel that mixes colors needs current adjustment for each color to look even.
Conclusion
This article provides a brief introduction to the seven most commonly used LED emitting colors. It discusses how LED defines color and how each LED factory defines their colors. Product designers have the option to choose the lowest-cost LED color from the early stages of the design process.
Related 7-Segment and 16-Segment Display Resources
Continue with these closely related resources to verify selection, circuit, and application requirements.
- What is SMD / SMA / SMT / SMC / SMP / SME? What’s the difference?
- How to design an LED series current-limiting resistor for 7 segments LED display?
- Introducing 7-segment & 16-segment displays & internal structures.
- How to Represent Numbers and Letters in 7-segment and 16-segment LED display?
- What is RGB SMD LED? | SMD LED Packaging | Full Series RGB LED Comparison Table
- Choose the Lowest-Cost LED Color｜LED Color Cost Analysis
- Tooling cost of LED display? How to reduce it.
- What is THT (Through-hole technology)? Introduction to component types and assembly.
- Introduce dot matrix display’s name, type, internal structure, and application scene
- Using LEDs to display information! The four most common types of LED information displays
Emitting color is one of the things we can change on a custom part. If none of the seven most commonly used colors fits your product, see our custom LED display service for what else can be changed, the sampling schedule and how MOQ is quoted.